Pressure sensitive record material



Patented Apr. 25,, 195% ifittgii? NtTED STATES PATENT OFFICE PRESSURE SENSITIVE REGGRD MATERIAL Barrett K. Green, Dayton, Uhio, assignor to The National fiash ltegistcr Company, Dayton, Ohio,

a corporation of Maryland N Drawing.

Original application November 8,

1947, Serial No. 784,938. Divided and this application November 10, 1948, Serial No. 59,427

Glaims. i

provide a pressure-sensitive record material in which the mark of distinctive color will be produced only at the points of application of localized pressure, and at no other points, and under no other conditions.

Another object of this invention is to provide a pressure-sensitive record material in which the mark of distinctive color is produced by the chemical reaction of color-forming reactants, in

the mere application of localized pressure and M} the absence of any liquid inoizing medium therewhich is not subject to the disadvantages infor. herent in the pressure-sensitive record material A further object of this invention is to prodisclosed in United States Letters Patent No. vide a pressure-sensitive record material in 2,299,693, patented October 20, 1942, on the apwhich a mark of distinctive color is produced by plication filed by Barrett K. Green on February is a reaction between solid particles of color-form- 23, 1940. That patent discloses a pressureing reactants. sensitive record material including the combina- Further objects, and objects relating to detion of an insulating medium, a rupturable solid tails and economies of production, will definitely material such as gum dammar, having included appear from the detailed description to follow. therein interspersed droplets of a plurality of m The objects of this invention have been attained liquid reagents, which are chemically reactive to m by the several embodiments thereof described produce a distinctive color in the record matein detail in the following specification. This inrial at the points of application of localized vention is clearly defined and pointed out in pressure thereto, such pressure rupturing the the appended claims. insulating medium to p t C e c l ea In general, the present invention contemplates between the two liquid reagents. The two rea pressure-sensitive record material comprising, agents disclosed in this patent are gallic acid in combination, a plurality of adsorption colorand ferric ammonium sulphate, each dissolved in forming reactants, such reactants being so seglycerine. These reagents are ionized by the lected that they react, in the absence of a liquid glycerine, which constitutes an ionizing medium, ionizin medium for the reactants, to form a disand the chemical reaction proceeds by intertinctive color when brought into adsorption conchange of ions when the two solutions are altact with each other, and a solid insulating medilowed to mix, upon the rupture of the insulatum insulating said reactants from color-forming ing medium. The reaction disclosed in that reaction contact with each other. Upon applicapatent depends upon the presence of the retion of localized pressure to the record material, agents in an ionizing medium. However, any as by drawing a stylus across it, the insulating available ionizing medium is hydroscopic, with medium is ruptured at the points of application the result that the record material made in acof said localized pressure, and such rupture percordance with this patent is sensitive to an exmits color-forming reaction contact between the cess of moisture, and conditions of high humid- 49 reactants at such points, in the absence of any ity may cause the insulating medium to cease liquid ionizing medium for said reactants. The to be effective, with the result that the chemiresult is that a mark of distinctive color is procal reaction takes place without any application duced by the mere application of localized presof localized pressure, and the record material is sure. stained and discolored, so that it ceases to be The color-forming reaction employed is of the, useful. so-called, adsorption type in which an inorganic As stated above, the principal object of the compound causes a color change in an organic present invention is to provide a pressure-sensicompound When in adsorption contact therewith. tive record material that is not subject to the Of the reactant materials employed the organic defects and disadvantages of that disclosed in 50 material is an electron donor aromatic compound Patent No. 2,299,693, as indicated above. having a double bond system which is convertible Another object of the present invention is to to a more highly polarized conjugated form upon provide a record material upon which a mark of taking part in an electron acceptor-donor solid distinctive color may be produced, at the points surface chemical reaction, giving it a distinctive of application of localized pressure thereto, by color, and the inorganic material is a material such mere application of localized pressure, and which is an acid relative to the organic material which will not become discolored or stained due so as to be an electron acceptor when in adsorpto the effect of light, atmospheric conditions, 01' tion contact therewith. Both materials are in aging. fine particle form in order to furnish a large In short, it is the object of this invention to reactant surface area per unit area of the record it material which enhances the depth of color per unit area of the record material.

In the preferred form of this invention, both of the color-forming reactants, as well as the insulating medium, are in the solid state, and.

the color-forming reaction takes place upon mere contact of solid particles of the reactants. it. pressure-sensitive record material may be provided in which the solid particles of a plurality of color-forming reactants are dispersed in a solid insulating medium, which insulates the particles from color-forming reaction contact with each other. The rupture of this solid insulating medium by the application of localized pressure permits the solid particles of color-forming reactants to react with each other, atthe points. of application or suchpressure, toproduce the mark of distinctive color. According to. one form of this invention, solid particlesoi one of the. colorforming reactants are carried. by and dispersed in a solid insulatingmedium, to which a coating of solid particles of another color-forming reactant is applied. In this case, the application. of localized pressure ruptures the solid insulatin medium at .the points of application of such pressure and brings about color-forming reaction contact between the solid particles of color-forming reactants at such points, thus producing the mark of distinctive. color. Preferably, this pressuresensitive record material. includes a base web, such as a fibrous web of paper or the like, to which the coating. of. solid insulating medium: and the color-forming reactants is applied.

Since it is difficult to. show precisely the spatial relationship. between the solid particles of color- 3 forming reactants, the. .Solid insulating medium, and the base web, it is preferred not to attempt to illustrate any embodiment of this invention by drawings.

In: the following examples, there will be de- I This record material is normally white, but the application of localized pressure thereto ruptures the insulating medium, casein, at the points of application of such pressure, permitting colorforming reaction contact between the solid particles of kaolin and the solid particlesof the com pound 3,3 bisp-"nethylaminophenyl) phthalide, resulting in the production of a bright blue mark.

The record material just described has been successfully made by coating a. web of paper with a casein solution having solid particles of kaolin dispersed therein, the ratio of kaolin to casein being about ten to one. The paper so coated was dried, and the coated side of thep'aper was treated with a 3%. solution in toluene of the compound 3,3. bis(pqrnethylaminophenyl) phthalide. The excess of solution was removed, and the treated a paper was dried to evaporate the solvent.

The compound 3,3 bis(p-m thylaminophenyl) phthalide, referred to above, is described and .claimed in the pending application of Clyde S. .Adams, Serial No. 588,077, filed April 12, 1945,

now Patent-No. 2,474,084, for Secondary amines of 3,3 bis(p-a1ninophenyl) phthalide.

Another embodiment of this invention is a pressurersensitive, record material consisting of a web of paper having applied thereto a coating consisting of casein as the solid insulating medium and solid particles of two color-forming reactants; namely, kaolin and the compound 3,3 bis- (pethylaminophenyl) phthalide, having the structural formula This record material isnormally white, but the application of localized pressure thereto ruptures the solid insulatingv medium at the points of application of. such pressure, thus permitting color-forming reaction contact between the solid particles of kaolin and. 3,3- bis. (p-ethylaminophenyl) phthalide, resulting. in a bright blue mark.

The record material. described above was successi'ully made by coating a webof paper witha casein solution having solid particles of kaolin interspersed therein, the ratio of kaolin to casein being about ten to one. The coating so applied having been dried,.fthe coated side of the paper wastreated with a 3% by weight solution in toluene of the compound 3,3 bis(p-ethylaminophenyl) phthalide. The excess of this solution was removed and the treated paper dried to evaporate the solvent.

The compound 3,3 bisip-ethylaminophenyl) phthalide, referredto above, is described and claimed in the pending 'application of Clyde S. Adams, Serial No. 588,077, filed April '12, 1945, for Secondary aminesof 3,3 bis(p-aminophenyl) phthalide.

When these ingredients are applied to the paper as a coating thereon,- such coating should weigh about .0023 pound per square foot of surface and may have a thickness o'fl'the order of from .0005 to .001 inch. The thickness of the coating varies, of course, with the treatment to which the record material is subjected in'finishing. The solid particles of kaolin in this record material may be of about the order of ten microns in diameter, although considerable variation in particle size 'is possible without any ill effects. Particle size of thephthalide compounds is largely determined by the method of application of those ingredients. The particles ofthe'se; reactants may be as large as tenmicrons indiameter and frequently are-much smaller.

Grganic fiim' forming hydrophilic colloid mate'- rials' such as" gelatin, methylcellulose, starch, polyvinyl alcohol, and animal glue are representative materials that may be substituted for casein as the-solid insulating-medium. Any of the following inorganic materials may be substituted for-kaolin as one oi the color-formingreactants;

attapulgite (Attapulgus clay), pyrophyllite, talc, bentonite, halloysite, calcium sulphate, calcium citrate, magnesium trisilicate, zinc sulphide, zirconium dioxide, calcium phosphate, barium sulphate, and calcium fluoride. When any of these materials are substituted for kaolin in this combination, the resulting record material will be White or bluish white in color, and a bright blue mark will appear thereon as the result of the application of localized pressure.

One method that has been used successfully to make the pressure-sensitive record materials described above is as follows: A slurry of kaolin and Water was prepared including fifty parts by weight of kaolin to fifty parts by weight of water, and a small amount of a. suitable dispersing agent, such as sodium metaphosphate, for instance, in the proportion of 0.75% by weight was added to facilitate the dispersion of the particles of kaolin throughout the slurry. lhe addition of this dispersing agent reduces the viscosity of the slurry considerably, thus facilitating its mixing and application and also preventing the settling of the solid particles of kaolin. A 20% by weight solution of casein in water was formed by, first,

dispersing the casein in cold water by stirring for fifteen minutes at room temperature and, then, heating up to 60 degrees centigrade. Five parts by weight of a 28% ammonium hydroxide so1ution--that is, one having a specific gravity of 259 B., at

were then added to the hot casein solution, which was stirred for about fifteen minutes and allowed to cool to room temperature. The kaolin slurry and the alkaline casein solution were then thoroughly mixed and blended in the ratio of ten parts by Weight of kaolin to one part of casein, and, at this stage, a small percentage-for in stance, about 0.05% by weight-of tributyl phosphate in alcohol, or other anti-foaming agent, was added. This mixture of the kaolin slurry and the casein solution was then applied as a coating to the paper, and the coated paper was dried and calendered or treated in any desired way to give the proper surface finish. A solution in toluene of about 3 by weight of the phthalide compound was then applied to the coated side of the paper, the excess of this solution Was removed in any suitable way, as by passing under a doctor blade, and then the treated paper was dried to evaporate the toluene and was ready for use.

The methods and processes of making pressuresensitive record material disclosed herein are not claimed in this application but are disclosed and claimed in the pending application of Barrett K. Green, Serial No. 784,939, filed November 8, 1947, for Process for makin pressure-sensitive record material, and the division thereof, Serial No. 63,216, filed December 2, 1948.

It is understood that the pressure-sensitive record material described herein is susceptible of considerable variation without departing from the spirit of the invention.

What is claimed is:

l. Pressure-sensitive record material including the combination of a supporting member, a plurality of adsorption color-forming reactants in the solid state, so selected as to react in the absence of a liquid ionizing medium for the reactants to form a distinctive color when brought into contact with each other, at least one of the reactants being an inorganic compound and at least one other reactant being an organic compound, disposed in proximity to each other, and a solid insulating medium, derived from a filmforming hydrophilic colloid substance, insulating said reactants from color-forming reaction contact with each other, the application of localized pressure to the record material rupturing said insulating medium at the points of application of such pressure to permit color-forming reaction contact between the reactants at such points, whereby a mark of distinctive color is produced by mere application of localized pressure, one of said color-forming reactants being an organic compound of the structure RHN NHR wherein R is selected from the group consisting of CH3 and C2H5, and the inorganic reactant being in line particle form to provide a large adsorbent surface area and which is an acid relative to the organic compound so as to be an electron acceptor when in adsorption contact with the organic compound, the organic compound and the inorganic material being adsorbable one upon the other.

2. The record material of claim 1 in which the inorganic color-forming reactant is kaolin.

3. The record material of claim 2 in which the solid insulating medium is casein.

4. Pressure-sensitive record material including the combination of a supporting member, solid particles of a plurality of adsorption color-forming reactants disposed in contiguity to each other, and a, solid insulating medium, derived from an organic film-formin hydrophilic colloid material, insulating said solid reactant particles from colorforming reaction contact with each other, at least one said reactants being an inorganic material and at least another one of said reactants being an organic material one adsorbable on the other, said reactants being so selected as to react to form a distinctive color when particles of each are brought into adsorption contact, the applica tion of localized pressure to the record material rupturing said insulating medium at the points of application of such pressure to permit colorforming reaction contact of the solid reactant particles at such points, whereby a mark of distinctive color is produced by mere application of localized pressure, one of said color-forming reactants being an inorganic compound of the structure RHN NHR 7 organic compound so as to be an electron acceptor; when in adsorption. contact. with; the organicccompoundc 5. The, record. material, of: claim: a, in which the: inorganic colors-forming reactant is: kaolin;

6-.. The. recordymaterial. of: claim. 5 in which the solid insulatingpmediumzis; casein.

'7. Pressure-sensitive: record material including the. combination. of a supporting member a, solid insulating 'meolium', derived from; an. organic. hy-

drophilic. colloid substancasolid. particles. of a first .color-iormingreactantldispersed therein and solidparticleszof asecond color-forming reactant depositedthereon, said. solid insulating medium insulating said solid reactantparticlesfrom.colore forming reaction contact with each other, one of said reactants'being an inorganic compound and the other reactant being, an organic compound one adsorbable on the other, said reactants being so selected asto react, in the solid state, to form a distinctive color when brought into adsorption contact with each other, the application of localized pressure to the record material rupturing said insulating medium at the points of application of such pressure to permit colorforming reactioncontact of. the solid reactant particles at such. points, whereby a. mark of dis.-. tinctive color is produced by. more application of localized pressure, the second of said. colorforming reactants being an organic compound of the structure.

RHN

wherein R is selected from the group consisting of CH3 and C2315, and the second reactant is in organic material in fine; particle form providing a large adsorbent surface area and which is an acid relative to the organic compound so. as to be an electron acceptor when in adsorption con.- .tact with the organic compound.

8. The record material of claim '7 inwhich the first color-forming reactant is kaolin.

9. Ihe record material of claim I inwhich the solid insulating medium is casein.

10. Pressure-sensitive record material including the combination of a base-Web and a coating thereon, said coating including a plurality of adsorption color-forming reactants in'thesolid, state, so selected as to react in the absence 'ofan ionizingmedium to form a distinctive color when brought into contact with each other, at least one of the reactants. being an inorganic compound and at least another of the reactants being d an organic compound one adsorbable: upon, the other, and. disposed in proximity. to each. other, and a..solid insulating :medium, derived. from. an organic film-forming.- hydrophilic; colloid Sub:-

- stance, insulating said reaota-nts from color-.formi-ng. reaction contact; with. each other, the. applicationaof localizedipressure to the record material rupturing said insulating medium. atv the. points of. application of such pressure to permit colorforming reaction contact between the reactants at such: points, whereby. a mark of. distinctive color is. produced by: mere application of localized pressure, one oi-said color-forming reactants be-.. ing. an organic compound Qf'the structure wherein R is selected from the group consisting of CH3 and Cz-Hs and the inorganic material is in fine particle form to provide a large adsorbent surface areaand is an acid relative to the organic compound so as to-be anelectrondonor when in adsorption contact with the organic compound. 11. The record material of claim' 1-0 in which the inorganic color-forming reactant is kaolin. 12. The record material'of claim 11 in which the solid insulating medium is casein.

13. The record material. of claim l in R is CH3..

14.. The Ris CH3.

15. The R is'CHs.

16. The Ris'CI-la.

17. The Ris CzH's.

18. The R is C2Hs. Y 19". The R. is C2H5. 20. The R is CzHs.

which record materialof claim 4 in which record material of claim 7 in which record material ofclaim 10 in which record material of claim I in which record material of claim 4 in which record material of claim 7 in'which record material of claim 10in which BARRETT K. GREEN.

REFERENCES CITED The following references are of record in the file. of this patent:

FOREIGN PATENTS Number Country Date 550,332 Great Britain Jan. 4, 1943 

1. PRESSURE-SENSITIVE RECORD MATERIAL INCLUDING THE COMBINATION OF A SUPPORTING MEMBER, A PLURALITY OF ADSORPTION COLOR-FORMING REACTANTS IN THE SOLID STATE, SO SELECTED AS TO REACT IN THE ABSENCE OF A LIQUID IONIZING MEDIUM FOR THE REACTANTS TO FORM A DISTINCTIVE COLOR WHEN BROUGHT INTO CONTACT WITH EACH OTHER, AT LEAST ONE OF THE REACTANTS BEING AN INORGANIC COMPOUND AND AT LEAST ONE OTHER REACTANT BEING AN ORGANIC COMPOUND, DISPOSED IN PROXIMITY TO EACH OTHER, AND A SOLID INSULATING MEDIUM, DERIVED FROM A FILMFORMING HYDROPHILIC COLLOID SUBSTANCE, INSULATING SAID REACTANTS FROM COLOR-FORMING REACTION CONTACT WITH EACH OTHER, THE APPLICATION OF LOCALIZED PRESSURE TO THE RECORD MATERIAL RUPTURING SAID INSULATING MEDIUM AT THE POINTS OF APPLIATION OF SUCH PRESSURE TO PERMIT COLOR-FORMING REACTION CONTACT BETWEEN THE REACTANTS AT SUCH POINTS. WHEREBY A MARK OF DISTINCTIVE COLOR IS PRODUCED BY MERE APPLICATION OF LOCALIZED PRESSURE, ONE OF SAID COLOR-FORMING REACTANTS BEING AN ORGANIC COMPOUND OF THE STRUCTURE. 